ECGs Part 1.

By Clare Di Bona Education Session 1

Acknowledgement to Life in the Fastlane ECG Library

ECG Interpretation

  Rate   300/the number of big squares between R

waves or   Number of QRS complexes on rhythm strip

x6

ECG Interpretation

  Rhythm   Look at the pattern of QRS complexes

regular or irregular   Are P waves present?   What is the relationship between P

waves and QRS complex?

ECG Interpretation

  Axis

Axis

ECG Interpretation

Coronary Artery Anatomy

Coronary Artery Anatomy

Differential Diagnosis Chest Pain

  Write down a DDx for chest pain with distinguishing ECG features where relevant.

Diagnosis Distinguishing Features ECG features

STEMI Pale, clammy, pain requiring morphine

ST elevation ≥2mm on contiguous precordial leads or ≥1mm on contiguous limb leads

NSTEMI Horizontal or downsloping ST depression ≥0.5mm on two contiguous leads

Pneumothorax History of PTX, slender tall man, hx trauma, high RR

Pericarditis +/- effusion Pleuritic pain, relieved sitting forward Widespread ST elevation and PR depression. Reciprocal changes aVR

Pneumonia Preceeding URTI or flu-like symptoms, fever

Pulmonary Embolism Leg symptoms, decreased saturations, respiratory symptoms with clear CXR

Sinus tacchy, RBBB, RAD, R sided strain (t wave inversion V1-4 +/- inferior leads), S1QIIITIII

Esophageal Rupture Intense pain, history of recent endoscopy, hx oesophageal cancer

Ruptured peptic ulcer Peritonitic, sudden onset pain

Cholecystitis Murphy positive

Pleurisy

Differential Diagnosis for ST Segment Elelvation

  Write down 5 DDx for ST segment elevation on an ECG

Differential Diagnosis ST elevation on ECG   Myocardial Infarction   Coronary vasospasm (Printzmetal’s angina)   Pericarditis   Benign early depolarisation   LBBB   Left ventricular hypertrophy   Ventricular Aneurysm   Brugada Syndrome   Ventricular Paced Rhythm   Raised Intracranial Pressure

ECG 1

Anterior STEMI

  How do you recognise an anterior STEMI?   There is ST elevation and Q waves in

…………….leads   There is reciprocal ST depression in the

…………..leads

Anterior STEMI

  There is ST segment elevation in precordial leads (V1-6) and high lateral (I, aVL)

  There is ST depression in inferior leads (II, aVF)

How bad is it?

  Does anterior or inferior MI have a worse prognosis?

  Give 4 high risk presentations on anterior MI?

Anterior MI

  Anterior MI has a worse prognosis than inferior MI

  Total mortality 27% versus 11% due to the larger infarct size

Anterior MI

  Four high risk presentations of anterior MI

  1) LMCA   2) LAD   3) Wellen’s   4) De Winter’s T waves

Treat the Patient

  How long should it take you to sight the first ECG in a chest pain patient?

  How long from when you diagnose a STEMI to when they are on their way to the cath lab?

Treat the Patient

  The ECG should be sighted immediately   Diagnosis of STEMI needs to be

immediate   Under these circumstances you need to

be FAST.   Get senior help NOW, more nurses to

help NOW.   Aim to get out the door in 12 minutes.

STEMI Protocol

ECG 2

Lateral MI

  Infarction of the lateral wall   Recognised by ST elevation in I, aVL,

V5,V6   Reciprocal ST depression III, aVF

ECG 3

Interpretation

  Widespread ST depression   ST elevation aVR   This indicates either proximal LAD

occlusion or LMCA occlusion or severe triple vessel disease

  ST elevation aVR>V1 indicated LMCA rather than LAD.

Clinical Implications of ST elevation in aVR

  LMCA stenosis is bad-70% mortality without surgery/stent

  Urgent angiography is needed (not at 3am unless ongoing pain despite optimal medical treatment, can wait for 8am morning list)

ECG 4

Inferior MI

  ECG features:   ST elevation in II, III, aVF   Reciprocal ST depression aVL

Inferior MI

  Has a BETTER prognosis than anterior MI   40% associated RIGHT SIDED INFARCT   Right Sided infarcts develop SEVERE

hypotension in response to nitrates   RIGHT SIDED INFARCT MAY NEED FLUID

NOT NITRATES   20% inferior MI assoc severe bradycardia

from 2nd or 3rd degree AV block

Inferior MI

  80% of the time assoc occlusion of the R coronary artery

  18% of the time due to occlusion of left circumflex a

ECG 5

Inferior and R sided STEMI

  40% of the time inferior infarct is assoc R sided infarct

  NEED TO DO R SIDED LEADS IN INFERIOR MI

  ECG characteristics suggest R sided involvement   ST elevation V1   ST elevation lead III> lead II

Right Sided Infarct

  Complicates 40% of Inferior STEMIs   Extremely uncommon to have isolated R

ventricular infarction   Preload sensitive   Hypotension will result if give nitrates   Hypotension is treated using fluid

loading   Nitrates are contra-indicated

Right Sided Infarct

  How do you diagnose it?   NEED TO SUSPECT IN ALL PATIENTS

WITH INFERIOR STEMI   Suggested by

  presence of ST elevation V1   ST elevation III>II

Right Sided Leads

ECG 6

Posterior MI

  Occlusion of Left circumflex   Horizontal ST depression V1-3   ST elevation in leads V7-V9

Posterior MI

  ST elevation and Q waves in posterior leads V7-9

Posterior MI with Posterior Leads

Myocardial Ischaemia (NSTEMI, Unstable Angina)

  The difference is usually retrospective once the troponin result is known

  Same ECG changes   ST depression and T wave flattening or

inversion especially dynamic changes are highly suggestive of MI.

Patterns of Myocardial Ischaemia

  ST segment depression   T wave flattening or inversion   Hyperacute T waves   U-wave inversion

Patterns of Myocardial Ischaemia

Horizontal or downsloping ST depression ≥ 0.5mm at J point in ≥2 contiguous leads indicates myocardial ischaemia.

Upsloping is non-specific

The deeper the ST depression the higher the mortality≥2mm in 3 contiguous leads is 35% 30 day mortality.

Widespread ST depression

ST depression

  ST depression due to subendocardial ischaemia is usually widespread

  If there is also ST elevation aVR>1mm suggests LMCA occlusion

  ST depression in a particular territory ie septal, inferior or high lateral lateral can represent reciprocal change and the corresponding ST elevation should be sought.

T wave inversion

  More likely to be significant if   At least 1mm deep   ≥2 contiguous leads with dominant R

waves   Dynamic ie not present on old ECG or

changing over time

Wellens’ Syndome

  Deep T wave inversion in V2 and V3 suggestive of stenosis of proximal LAD

  Type 1 Wellens’ deep symmetrical waves

  Type 2 have biphasic T waves with the initial deflection positive

So How Do I Treat NSTEMI and Unstable Angina   ABC   History and Exam   12 lead ECG (repeat every 15 minutes until chest

pain resolves)   Cardiac monitor   02 to keep Sats >90%   IV access and bloods   Aspirin load   Nitrates and Morphine unless contra-indicated   Additional Platelet agent and Heparin infusion after

consultation with senior or cardiology

How Do I Identify Patients that are High Risk

  High Risk Features:   ST depression in two or more contiguous leads   Raised troponin   TIMI score ≥5   Persistent pain despite optimal medical therapy   Haemodynamic compromise

THESE PATIENTS ARE IN NEED OF A MORE URGENT ANGIOGRAM.

Choice of Stress Testing in the Outpatient Setting (McLellan 2012)

Web Based ECG Learning   Burns, E. Life in the Fastlane: ECG Library [Internet]

Available from: http://lifeinthefastlane.com/ecg-library/

  John, L. Emergucate: ECG of the Week [Internet] Available from: http://www.emergucate.com/ecg-of-the-week/

  JEDO STEMI Protocol. Available from: http://jhced.org clinical guidelines

  McLellan A. Cardiac Stress Testing. Australian Family Physician. 2012 March 41 (3): 119-122.

  Coronary anatomy [Internet] Available from: www.radiologyassistant.nl